1. Field of the Invention
The present invention relates to a navigation system consisting of a server and in-vehicle terminal, and in particular, to a navi-server controlling traffic information and a navigation apparatus outputting the traffic information by making data communications with the navi-server
2. Description of the Prior Art
A conventional navigation apparatus notifies a driver of information such as a traffic jam and traffic regulation provided from a traffic information center through an FM multi-broadcast, electric waves/light beacons, and telephone networks by displaying the information in characters and simple graphics and displaying it overlapped on a map. Generally, the traffic information draws a traffic jam road and parallel line thereto beside a road, and represents a traffic jam degree by a color of the line and a traffic jam length by a length of the line. In addition, by performing a dynamic route search taking into consideration the traffic information and providing users with a shortest time route, the driver can know the traffic information centered on a position of his/her car and smoothly drive it.
Incidentally, the traffic information is information at a certain time in a near past, and therefore the driver cannot judge whether a traffic jam will be eliminated or aggravated more and more hereafter. Consequently, Japanese Patent Laid-Open Publication 2001-124577 has proposed a method for performing an animation display that shows whether a traffic jam will be improved or aggravated hereafter, and another method for displaying graphics showing an increase trend and decrease trend of the traffic jam on a map. For example, it is proposed to show a traffic jam extending trend by thickening a back end of an arrow mark and a traffic jam diminishing trend by thinning the back end of the arrow mark.
However, the conventional technology cannot judge whether provided traffic jam information is a traffic jam that frequently occurs or an abrupt one due to an accident and construction. In addition, if the information is a traffic jam that frequently occurs, it is difficult to judge how many hours it usually takes for the traffic jam to be eliminated.
Incidentally, it is difficult for a user to identify a traffic jam trend according to a slight difference of a graphic shape on a small display for use in an in-vehicle terminal. And such an animation display is not preferable from a viewpoint of eyes free since it captures driver's attention. Moreover, when displaying an extending/diminishing trend by deforming a graphic such as an arrow mark, a terminal cost increases since an exclusive graphics LSI and the like performing a graphics processing such as a texture mapping is needed.